Not Applicable
Sumps have been around nearly as long as there have been homes exposed to areas where high water tables exist such as lakes, rivers and those areas where soils or landscaping are unsuitable for adequate drainage. Typically, drain tiles are used to funnel perimeter water into the sump basin. A pump is used to expel the water from the basin. A sump pump switch is used to sense the liquid level and supply current to the pump so that the pump can remove the basin water.
There are various systems used to sense the basin liquid and switch the pump on so that water is expelled. There are vertically actuated float switches, tethered float switches, magnetically actuated reed switches, diaphragm switches, and probe systems.
Some sump pumps that use pump switches with exposed floats can vibrate over into the basin wall causing the float system to fail to operate the pump switch. Floats may also be subjected to debris collection that may cause float system failure. Some product solutions to float related problems have involved floats moving vertically inside a column. The column requires hole(s) to allow the liquid to raise the float. Column holes are subject to blockage by environmental debris.
Other alternatives to float operated systems are diaphragm switches. Diaphragm switches have requirements for a vent tube or breather to relieve the pressure on the non-liquid side of a liquid operated diaphragm. Often the vent tubes/breathers are located where they can get crimped or plugged with debris, insects or objects associated with user curiosity such as inside the power cable. If a sufficient pressure differential is not achieved before the non-liquid side vent is plugged, the diaphragm may not deflect enough to reliably operate the switch within the confines of the basis. All diaphragm switches that directly interface (contact) with a mechanical switching mechanism are subject to the variability in the activation and release forces inherent in the mechanisms. Variability in these forces is inevitable due to the variability in the manufacturing process and the physics associated with contacting mechanical moving parts. When these forces are used to dictate the system on and off set points, these set points will be inconsistent from switch to switch and cycle to cycle. With this kind of variability, in the switching mechanism, the lower level set point shifting too much could cause possible vortexing and cavitating thereby causing pump failure. If the upper level set point shifts too much then the basin could overflow depending on the mounting location of the pump switch which generally is limited to the discharge tube.
Probe systems take advantage of the conductivity of the sump basin water to sense the liquid before switching power to the pump. Since probes are in contact with the sump water, they are also subject to lime and calcium build-up which will not conduct. This loss or increase in impedance through the sump water can cause system failure since current can no longer flow sufficiently to allow sensing of the liquid. If the liquid is not sensed, power can not be switched to the pump so that the pump cannot expel water from the basin.
Noting the observed faults above, the present invention utilizes a flexible diaphragm, waterproof/breathable membrane for pressure relief, and a pair of repelling magnets that are used to reliably and accurately operate a switching mechanism that is dependent on a liquid level. In addition, an air trapping diaphragm retainer is incorporated that assists in controlling the consistency of the pumping range while extending the life of the diaphragm.
The embodiment of the invention provides a control apparatus for turning on and off an electrical control load device after sensing a high and low liquid level in a chamber. The apparatus includes an electrical control circuit and a liquid level sensing apparatus. The liquid level sensing apparatus converts liquid level pressure through the use of a movable diaphragm into a directed internal force used to actuate the electrical control apparatus. The directed internal force is controlled by the characteristics of repelling magnets configured to move such that the magnets axial center lines are aligned at actuation. Before the alignment can occur, the magnets must be offset vertically and horizontally such that the desired actuating force dictates the upper level set point. When in the first position, a high repelling force component impedes activation due to the close proximity of the offset magnets. When a magnitude of force associated with the liquid pressure is sufficient to overcome the repelling force component of the first position, the piston rod translates to the second position. When in the second position and the oriented repelling magnets are axially aligned (while maintaining a greater air gap than when in the first position), the repelling force component is lower than when in the first position. In summary, the repelling force component associated with the offset repelling magnet is greater in the first position than in the second position. The difference between force components (that are perpendicular to the plane of orientation of the diaphragm) while in the first and second positions dictate the pumping range for the load control apparatus.
Before the load control apparatus can be actuated, water pressure must reach a level that provides enough energy to overcome the natural semi-static force associated with the offset repelling magnets. Once this force barrier is overcome, the piston rod with drive magnet accelerates into the actuating position thereby causing near axial alignment of the drive and driven magnets. Once alignment occurs, the primary applied magnetic force vector changes magnitude and direction. The primary applied magnetic opposing force vector changes instantaneously by 90 degrees thereby providing the primary resultant force vector with enough energy to move the load control apparatus actuating member. As the load control apparatus actuating member with mounted driven magnet is repelled away from the drive magnet, the resultant force vector changes, causing the load control apparatus actuating member with mounted driven magnet to rotate to the actuating position. This change in the angular displacement of the axial center lines of the drive and driven magnets produces a component force vector that dictates the lower level set point while in position two. As the liquid level in the chamber is reduced, the water pressure is reduced on the diaphragm. Once the liquid level pressure falls below the threshold of the downward deactivation force component on the drive magnet, the magnets will return to their original offset position and the load control apparatus actuating member will return to its original position thereby causing deactivation of the load control apparatus.
Internal pressure changes caused by the diaphragm""s bi-directional motion are vented by a waterproof/breathable membrane. The membrane is protected from premature blockage by environmental debris through the use of an opened bottom, cover. Environmental debris may include but is not limited to dust, dirt, chemicals and surface water particulate. If the electrical load should fail to control a liquid level, the membrane will remain protected from environmental contaminates even if the liquid should encapsulate the entire control apparatus. The low water pressure potential associated with sump basins will not compress the air in the air trapping protective cover to a level that would allow contact of the waterproof membrane.
A feature of the invention is in using a waterproof breathable membrane to relieve the internal pressure created by the motion of the diaphragm. An additional feature of the invention is in utilizing a phenomenon associated with varying magnetic forces as two repelling magnets move in the same plane and perpendicular to their axial center lines to control the accuracy of the upper and lower level set points of the pumping range.